Linear motor drive ultrahigh-speed injection moulding machine

This paper presents a report on the development of a linear motor drive injection moulding machine for the attainment of ultrahigh-speed injection moulding. Until now it has been impossible to produce such a high speed with all-electric injection moulding machines, although the need for such ultrahigh-speed, electrically driven injection moulding machines has clearly existed. However, direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of an inertia force as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic leakage. In this paper, two solutions are proposed for this inertia force problem. One is mechanical cancellation of the inertia force, the other is an increase in the nozzle contact force. Furthermore, a new nozzle contact mechanism is proposed that prevents the stationary platen bending caused by the nozzle contact force. Some experimental results on a manufactured all-electric, ultrahigh-speed injection moulding machine are presented.